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Cortina Systems LXT9785 and LXT9785E Advanced 8-Port 10/100 Mbps PHY Transceivers
LXT9785/LXT9785E
Datasheet
249241, Revision 11.0
16 April 2007
4.12 Monitoring Operations
4.12
Monitoring Operations
4.12.1
Monitoring Auto-Negotiation
Auto-negotiation may be monitored as follows:
Bits 1.2 and 17.10 = 1 once the link is established.
4.12.2
Per-Port LED Driver Functions
The LXT9785/LXT9785E incorporates three direct drive LEDs per port (LEDn_1_L,
LEDn_2_L, and LEDn_3_L).
On power up, all the LEDs lights up for approximately one second after reset de-asserts.
Each LED may be programmed to one of several different display modes using the LED
Configuration Register. Each per-port LED may be programmed (refer to
Table 97, LEDconditions:
Operating Speed
Transmit Activity
Receive Activity
Collision Condition
Link Status
Duplex Mode
Isolate Condition
The LEDs can also be programmed to display various combined status conditions. For
example, setting bits 20.15:12 = 1101 produces the following combination of Link and
Activity indications:
If Link is down, LED is off.
If Link is up, LED is on.
If Link is up AND activity is detected, the LED blinks at the stretch interval selected by
bits 20.3:2 and continues to blink as long as activity is present.
The LED driver pins are open drain circuits (10 mA max current rating). Refer to
Sectiondesign details. The LED Configuration Register also provides optional LED pulse
stretching to 30, 60, or 100 ms. If during this pulse stretch period, the event occurs again,
When an event such as receiving a packet occurs, it is edge detected and starts the
stretch timer. The LED driver remains asserted until the stretch timer expires. If another
event occurs before the stretch timer expires, the stretch timer is reset and the stretch
time extended.